The present invention relates to a liquid container. As a liquid ejecting apparatus that ejects ink droplets through nozzles of a liquid ejecting head, there is an ink jet printer. A liquid container (ink cartridge) storing a liquid (ink) to be supplied to the liquid ejecting head (print head) is detachably mounted in this ink jet printer. The ink cartridge is made up of a casing and members (e.g., a porous member, an ink containing bag, and a film valve) for holding the ink in the casing. To easily house such members in the casing, the casing normally comprises a body casing and a lid portion.
JP-A-5-16377 discloses an ink cartridge having a bag-like ink pack housed in a casing made up of a body casing and a lid portion. This lid portion is provided with a pair of horns and a pair of claw portions. At the same time, the body casing is provided with hole portions corresponding to the horns and recessed portions corresponding to the claw portions. And, after the ink containing bag is housed in the body casing, the horns of the lid portion are fitted into the hole portions, and the claw portions of the lid portion are engaged into the recessed portions of the body casing. Thus, the lid portion is attached to the body casing, thereby forming the ink container (ink cartridge). With such a configuration, the lid portion can be securely connected to the body casing. Besides, the lid portion can be detached from the body casing by simply releasing the engagement between the claw portions and the recessed portions and then disengaging the horns from the hole portions. Accordingly, the ink containing bag can be replaced, which can reproduce the lid portion and the body casing, thus enabling recycle usage of the ink container.
With the configuration of the ink cartridge of JP-A-5-16377, however, in manufacturing its lid portion or body casing, when a dimensional error occurs between the lid portion and the body casing due to a manufacturing error, the horns or claw portions of the lid portion shift relative to the hole portions or recessed portions of the body casing. This makes it difficult to attach the lid portion to the body casing, thus taking a lot of trouble over the operation of forming the ink cartridge.
Besides, recently, because of an increase in ink flow due to an increase in the print speed and fineness of the printer, an ink jet recording apparatus sometimes adopts the following means. That is, when ink is supplied to a recording head, air is flowed into the ink container, thereby pressurizing the ink containing bag. In this case, when the air is flowed into the ink container to pressurize the ink container bag, the inflow air pressurizes the lid portion from inside the ink container accordingly. Such pressurization bends the lid, portion, and the horns or claw portions of the lid portion moves accordingly, so that the lid portion becomes easy to come off the body casing, Thus, there is the problem that the reliability of the ink container will be reduced.
When the ink containing bag is pressurized by flowing the air into the ink container, it is necessary to increase the air pressure between the casing and the ink pack. Consequently, an opening of the casing for attaching the ink pack thereto need be hermetically sealed. As shown in FIG. 7, in an ink cartridge 151 of JP-A-2001-212973, a plug body 155 sealing an opening portion of an ink pack 154 projects to the outside from an opening potion 153 formed in a casing 152. In this state, an O-ring 156 is applied to the opening portion 153, while an engaging member 157 is pushed into the opening portion 153 from outside the casing 152, thereby hermetically attaching the plug body 155 to the opening portion 153.
Accordingly, in the ink cartridge having the bag-like ink pack or the like housed in the casing, a sealing member for improving sealing properties will be required and in addition, the structure of the sealing member will be complicated, thus increasing costs. Otherwise, the number of steps in assembling the apparatus increases in some cases.
The invention has been made to solve the aforesaid problems, and an object thereof is to provide a liquid container capable of maintaining airtightness while reducing the number of components and the number of assembly steps. Besides, another object is to provide a liquid container that can reduce the influence of a manufacturing error caused upon manufacture and has high reliability.
Additionally, the liquid container of the invention can be suitably Utilized as an ink cartridge of an ink jet printer including an off-carriage type of ink supply system, but is not limited thereto. For example, the liquid container of the invention is also applicable to a printer of the type that mounts thereto an ink cartridge mounted to a movable carriage disposed in the ink jet printer.
Here, the off-carriage type of ink supply system refers, for example, to a system that has an ink cartridge disposed on the side of a printer body and supplies ink from the ink cartridge via an ink supply tube or an ink replenishment mechanism, directly or via a sub-tank, to a print head mounted on the carriage movable to the body side.
The off-carriage type of ink supply system is suitably utilized in a printer that includes an ink cartridge of large capacity to print large prints and a printer whose size and thickness is reduced by mounting no ink cartridge on a carriage for a reduction in the size of the carriage.